Rectal Cancer / Colon Cancer
Colon cancer is cancer of the large intestine (colon), the lower part of your digestive system. Rectal cancer is cancer of the last 8 to 10 inches of the colon. Together, they are often referred to as colorectal cancers, and they make up the second-leading cause of cancer-related deaths in the United States. Only lung cancer claims more lives.
Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become cancerous.
Polyps may be small and produce few, if any, symptoms, so it's important to get regular screening tests to help prevent colon cancer. If signs and symptoms of cancer do appear, they may include a change in bowel habits, blood in your stool, persistent cramping, gas or abdominal pain.
Despite the relatively high number of cases and deaths, there's good news about colon cancer. Screening tests, along with a few simple changes in your diet and lifestyle, can dramatically reduce your overall risk of developing colon cancer.
Cancer affects your cells, the basic units of life. Healthy cells grow and divide in an orderly way to keep your body functioning normally. But sometimes this growth gets out of control — cells continue dividing even when new cells aren't needed. In the colon and rectum, this exaggerated growth may cause precancerous polyps (adenomas, or adenomatous polyps) to form in the lining of your intestine. Over a long period of time — spanning up
to several years — some of these polyps may become cancerous. In later stages of the disease, cancerous polyps may penetrate the colon walls and spread (metastasize) to nearby lymph nodes and other organs.
Polyps can occur anywhere in your large intestine, the muscular tube that forms the last part of your gastrointestinal tract. The colon comprises the upper 4 to 5 feet of your large intestine, and the rectum makes up the lower 4 to 5 inches. Your colon absorbs water, salt and other minerals from food and stores waste until it's eliminated from your body.
Polyps are either mushroom-shaped or flat and may be large or small. There are also several different types of colon polyps. Among the most common are :
- Adenomas. These polyps have the potential to become cancerous and are usually removed during screening tests such as flexible sigmoidoscopy or colonoscopy.
- Hyperplastic polyps. These polyps are rarely, if ever, a risk factor for colorectal cancer.
- Inflammatory polyps. These polyps may follow a bout of ulcerative colitis. Some inflammatory polyps may become cancerous, so having ulcerative colitis increases your overall risk of colon cancer.
Risk Factor :
Colon and rectal cancers can occur at any age, and no one is too young to develop colorectal cancer. However, about 90 percent of people with the disease are older than 50. Factors other than age that place you at a higher risk include :
- Inflammatory intestinal conditions. Long-standing inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase your risk.
- Family history. You're more likely to develop colorectal cancer if you have a parent, sibling or child with the disease. If many family members have colon cancer or rectal cancer, your risk is even
- greater. In some cases, this connection may not be hereditary or genetic. Instead, cancers within the same family may result from shared exposure to an environmental carcinogen or from diet or lifestyle factors.
Familial adenomatous polyposis (FAP) is a rare hereditary disorder that causes you to develop hundreds of polyps in the lining of your colon and rectum. If these go untreated, you'll likely develop colon cancer by age 40. In most cases, genetic testing can help determine if you're at risk of FAP. FAP may also cause noncancerous tumors to develop in other parts of your body, including your skin (sebaceous cysts and lipomas), bone (osteomas) and abdomen (desmoid tumors).
Hereditary nonpolyposis colorectal cancer (HNPCC) is another hereditary disorder that can put you at high risk of developing colon cancer or rectal cancer at an early age. Unlike FAP, however, you may have relatively few polyps.
If you're Jewish and of Eastern European descent, you may have an inherited tendency to develop colon cancer or rectal cancer. This is particularly true of Ashkenazi Jews.
- Diet. Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. Research is still occurring in this area. However, high-fiber, low-fat diets have additional health benefits apart from a potential connection to colorectal cancer prevention.
- A sedentary lifestyle. If you're inactive, you're more likely to develop colorectal cancer. This may be because when you're inactive, waste stays in your colon longer. Getting regular physical activity may reduce your risk.
- Diabetes. People with diabetes have up to a 40 percent increased risk of developing colorectal cancer.
- Smoking. More than one in 10 fatal colon cancers may be caused by smoking. Once diagnosed with colorectal cancer, smokers face a 30 percent to 40 percent increased risk of dying of the disease.
- Alcohol. Heavy use of alcohol may increase your odds of colorectal cancer.
- A personal history of colorectal cancer or polyps. If you've already had colorectal cancer or adenomatous polyps, you have a greater risk of colorectal cancer in the future.
When to seek medical advice :
If you notice any symptoms of colon cancer, such as blood in your stool or a persistent change in bowel habits, see your doctor as soon as possible. Keep in mind that colorectal cancer can strike younger as well as older people. If you're at high risk, don't wait until symptoms appear. See your doctor for regular screenings.
The American Cancer Society recommends colorectal screenings beginning at age 50 and more frequent or earlier screening if you have other risk factors, such as a family history of the disease.
Medicare has expanded its coverage of screening procedures. If you're older than 50 and have Medicare benefits, Medicare will cover annual fecal occult blood tests and sigmoidoscopy every four years. If you're at high risk of colorectal cancer, you'll be covered for colonoscopy every two years, or every 10 years if you're of average risk. Double contrast barium enema — which is sometimes supplemented with flexible sigmoidoscopy — can be used as an alternative, if your doctor thinks it's a better choice for you.
Like many people with colorectal cancer, you may have no symptoms in the early stages of the disease. When symptoms appear, they'll likely vary, depending on the cancer's size and location in your large intestine. In some cases, your symptoms may result from a condition other than cancer, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and sometimes diverticulosis or diverticulitis. Like colorectal cancer, these conditions are treatable.
See your doctor if you develop any of the following signs and Symptoms:
- A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool for more than a couple of weeks
- Narrow stools
- Rectal bleeding or blood in your stool
- Persistent abdominal discomfort, such as cramps, gas or pain
- Abdominal pain with a bowel movement
- A feeling that your bowel doesn't empty completely
- Unexplained weight loss
Blood in your stool may be a sign of cancer, but it can also indicate other conditions. Bright red blood you notice on bathroom tissue may come from hemorrhoids or minor tears (fissures) in your anus, for example. In addition, certain foods, such as beets or red licorice, can turn your stools red. Iron supplements and some anti-diarrheal medications may make stools black. Still, it's best to have any sign of blood or change in your stools checked promptly by your doctor because it can be a sign of something more serious.
Most colon cancers develop from adenomatous polyps. Screening is extremely important for detecting polyps before they become cancerous. It can also help find colorectal cancer in its early stages when you have a good chance for recovery.
Like many people, you may be embarrassed by the screening procedures, worried about discomfort or afraid of the results. Try not to let these concerns stand in your way. Most procedures are only moderately uncomfortable, and working with a doctor you like and trust should help ease your embarrassment.
Common screening and diagnostic procedures include the following :
- Digital rectal exam. In this office exam, your doctor uses a gloved finger to check the first few inches of your rectum for large polyps and cancers. Although safe and painless, the exam is limited to your lower rectum and can't detect problems with your upper rectum and colon. In addition, it's difficult for your doctor to feel small polyps.
- Fecal occult (hidden) blood test. This test checks a sample of your stool for blood. It can be performed in your doctor's office, but you're usually given a kit that explains how to take the sample at home. You then return the sample to a lab or your doctor's office to be checked. The problem is that not all cancers bleed, and those that do often bleed intermittently. Furthermore, most polyps don't bleed. This can result in a negative test result, even though you may have cancer. On the other hand, if blood shows up in your stool, it may be the result of hemorrhoids or an intestinal condition other than cancer. For these reasons, many doctors recommend other screening methods instead of, or in addition to, fecal occult blood tests.
- Flexible sigmoidoscopy. In this test, your doctor uses a flexible, slender and lighted tube to examine your rectum and sigmoid — approximately the last 2 feet of your colon. The test usually takes just a few minutes. It can sometimes be uncomfortable, and there's a slight risk of perforating the colon wall. If a polyp or colon cancer is found during this exam, your doctor will recommend colonoscopy to look at the entire colon and remove any polyps that are present for examination under a microscope.
- Barium enema. This diagnostic test allows your doctor to evaluate your entire large intestine with an X-ray. Barium, a contrast dye, is placed into your bowel in an enema form. During a double contrast barium enema, air is also added. The barium fills and coats the lining of the bowel, creating a clear silhouette of your rectum, colon and sometimes a small portion of your small intestine. There's also a slight risk of perforating the colon wall and the test has a significantly high rate of missing important lesions. A flexible sigmoidoscopy is often done in addition to the barium enema to aid in detecting small polyps that a barium enema X-ray may miss, especially in the lower bowel and rectum.
- Colonoscopy. This procedure is the most sensitive test for colon cancer, rectal cancer and polyps. Colonoscopy is similar to flexible sigmoidoscopy, but the instrument used — a colonoscope, which is a long, flexible and slender tube attached to a video camera and monitor — allows your doctor to view your entire colon and rectum. If any polyps are found during the exam, your doctor may remove them immediately or take tissue samples (biopsies) for analysis. This is done through the colonoscope and is painless. If you have adenomatous polyps, especially those larger than 5 millimeters in diameter, you'll need careful screening in the future.
You may receive a mild sedative to make you more comfortable. Preparation for the procedure involves drinking a large amount of fluid containing a laxative to clean out your colon — enemas are no longer necessary. Major risks of diagnostic colonoscopy include hemorrhage and perforation of the colon wall, but these are rare.
- Genetic testing. If you have a family history of colorectal cancer, you may be a candidate for genetic testing. This blood test may help determine if you're at increased risk of colon cancer or rectal cancer, but it's not without drawbacks. The results can be ambiguous, and the presence of a defective gene doesn't necessarily mean you'll develop cancer. Knowing you have a genetic predisposition can alert you to the need for regular screening. Still, you'll also want to consider the psychological impact of what the test may reveal. Knowing you may develop cancer affects not only your own life, but also the lives of everyone close to you. Genetic testing for children is even more complex and problematic. It's best if you discuss all of the ramifications of genetic testing with your doctor or a medical geneticist.
- New technologies. In the future, new technologies, such as virtual colonoscopy, may make colon screening safer, more comfortable and less invasive. In virtual colonoscopy, you have a two-minute computerized tomography scan, a highly sensitive X-ray of your colon. Then, using computer imaging, your doctor rotates this X-ray in order to view every part of your colon without actually going inside. Before the scan, your intestine is cleared of any stool, but researchers are looking into whether the scan can be done successfully without the usual bowel preparation. Although virtual colonoscopy potentially is a tremendous step forward, it's currently much less accurate than regular colonoscopy and doesn't allow your doctor to remove polyps or take tissue samples. This test is also not widely available.
Another new test checks a stool sample for DNA from abnormal cells. A clinical trial of this test by the National Cancer Institute is under way.
Staging your cancer
Once you've been diagnosed with colorectal cancer, your doctor will then also "stage" your cancer. Staging helps determine how well you'll do and what treatments are most appropriate for you. In both cases, the size of your tumor isn't as important as how far your cancer has spread. People being treated for colorectal cancer have a five-year survival rate higher than 90 percent if treated in an early stage, before it has spread. When cancer has spread to lymph nodes or nearby organs, the survival rate drops to less than 65 percent. The stages are :
- Stage 0. Your cancer is in the earliest stage. It hasn't grown beyond the inner layer (mucosa) of your colon or rectum. This stage of cancer may also be called carcinoma in situ.
- Stage I. Your cancer has grown through the mucosa but hasn't spread beyond the colon wall or rectum.
- Stage II. Your cancer has grown through the wall of the colon or rectum but hasn't spread to nearby lymph nodes.
- Stage III. Your cancer has invaded nearby lymph nodes but isn't affecting other parts of your body yet.
- Stage IV. Your cancer has spread to distant sites, such as other organs — for instance to your liver or lung, to the membrane lining the abdominal cavity, or to an ovary.
- Recurrent. This means your cancer has come back after treatment. It may recur in your colon, rectum or other part of your body.
The type of treatment your doctor recommends will depend largely on the stage of your cancer. The three primary treatment options are: surgery, chemotherapy and radiation.
Surgery (colectomy) is the main treatment for colorectal cancer. How much of your colon is removed and whether other therapies, such as radiation or chemotherapy, are an option for you depend on how far the cancer has penetrated into the wall of your bowel and whether it has spread to your lymph nodes or other parts of your body.
Your surgeon removes the part of your colon that contains the cancer, along with a margin of normal tissue on either side of the cancer to help ensure that no cancer is left behind. Nearby lymph nodes are usually also removed and tested for cancer. Your surgeon is often able to reconnect the healthy portions of your colon or rectum. But when that's not possible, for instance if the cancer is at the outlet of your rectum, you may need to have a permanent or temporary colostomy. This involves creating an opening in the wall of your abdomen from a portion of the remaining bowel for the elimination of body wastes into a special bag. Sometimes the colostomy is only temporary, allowing your colon or rectum time to heal after surgery. In some cases, however, the colostomy may be permanent.
In cases of rare, inherited syndromes such as familial adenomatous polyposis, or inflammatory bowel disease such as ulcerative colitis, you may need removal of your entire colon and rectum as a prophylactic measure. Then, in a procedure known as ileal pouch-anal anastomosis, your surgeon will likely construct a pouch from the end of your small intestine that attaches directly to your anus. This allows you to expel waste normally, although you may have several watery bowel movements a day.
Side effects of colon cancer surgery may include short-term pain and tenderness, and temporary constipation or diarrhea. If you have a colostomy, you may develop an irritation on the skin around the opening (stoma).
If your cancer is small, localized in a polyp and in a very early stage, your surgeon may be able to remove it completely during a colonoscopy. If the pathologist determines that the cancer in the polyp doesn't involve the base — where the polyp is attached to the bowel wall — then there is a good chance that the cancer has been completely eliminated.
Some larger polyps may be removed using laparoscopic surgery. In this procedure, your surgeon performs the operation through several tiny incisions in your abdominal wall, using small instruments with attached cameras that display your colon on a video monitor. He or she may also take samples from the lymph nodes that drain the area where the cancer is located. Studies have found that people undergoing this procedure need less pain medication and leave the hospital a day earlier on average. Also, people who have this procedure don't have higher rates of recurrence than those who choose the open surgery.
If your cancer is advanced or your health poor, only a small portion of your colon or rectum may be removed. This isn't as effective as surgeries that remove more tissue, and doctors mainly do this to relieve blockages or bleeding. This is referred to as palliative surgery; it isn't curative.
Chemotherapy uses drugs to destroy cancer cells. Chemotherapy can be used to destroy cancer cells after surgery, to control tumor growth or to relieve symptoms of colorectal cancer. Your doctor may recommend chemotherapy if your cancer has spread beyond the wall of the colon. In some cases, chemotherapy is used along with radiation therapy.
Possible side effects of chemotherapy include nausea and vomiting, mouth sores, fatigue, hair loss and diarrhea. If your doctor suggests aggressive treatment with multiple drugs, be sure you understand the side effects and risks as well as the potential benefits. If you're taking an oral chemotherapy medication, be sure you know the side effects to watch out for and report them to your doctor promptly.
Radiation therapy uses X-rays to kill any cancer cells that might remain after surgery, to shrink large tumors before an operation so that they can be removed more easily, or to relieve symptoms of colon cancer and rectal cancer. The goal of therapy is to damage the tumor without harming the surrounding tissue. If your cancer has spread through the wall of the rectum, your doctor may recommend radiation treatments in combination with chemotherapy after surgery. This may help prevent cancer from reappearing in the same place. Side effects of radiation therapy may include diarrhea, rectal bleeding, fatigue, loss of appetite and nausea.
Monoclonal antibody therapy
In 2004, the Food and Drug Administration approved two drugs from a new class of medications that treat colon cancer and rectal cancer by inhibiting the action of the cancer cells' growth factor. The drugs bevacizumab (Avastin) and cetuximab (Erbitux) are approved for use in people with colon cancer that has spread (metastatic cancer). Avastin is used in conjunction with standard chemotherapy and in a clinical trial added an average of five months to the study participants' survival time. Erbitux can be given on its own or in combination with the chemotherapy drug irinotecan (Camptosar). It's been shown to slow tumor growth and even shrink tumors, but there's currently no evidence showing that Erbitux can prolong survival.
Care following treatment
Follow-up care after treatment for colon cancer and rectal cancer is extremely important. During your regular checkups, you may have a physical exam, screening tests such as colonoscopy, chest X-rays to see if the cancer has spread, computerized tomography scans of your abdomen to look for enlarged lymph nodes and to see if the cancer has spread, and blood tests.
The most encouraging news about colon and rectal cancer is that you can actually reduce your risk by having regular screenings. That's because with regular screening, you can have polyps removed before they have a chance to turn into cancer. You can also protect yourself by making a few simple changes in your diet and lifestyle. The following suggestions may help save your life :
- Eat plenty of fruits, vegetables and whole grains. Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants, which may protect you from cancer. Try to eat five or more servings of fruits and vegetables every day, and to include a variety of produce in your diet.
- Limit fat, especially saturated fat. People who eat high-fat diets may have a higher rate of colorectal cancer. Be especially careful to limit saturated fats from animal sources such as red meat. Other foods that contain saturated fat include milk, cheese, ice cream, and coconut and palm oils. Try to restrict your total fat intake to about 30 percent of your daily calories, with no more than 10 percent coming from saturated fats.
- Get your vitamins and minerals. Calcium, magnesium, pyridoxine (vitamin B-6) and vitamin B-9 may help reduce your risk of colorectal cancer. Good food sources of calcium include skim or low-fat milk and other dairy products, shrimp, tofu and sardines with the bones. Magnesium is found in leafy greens, nuts, peas and beans. Food sources of vitamin B-6 include grains, legumes, peas, spinach, carrots, potatoes, dairy foods and meat. Folate is the natural form of vitamin B-9. It's found in certain foods naturally, including dark leafy greens such as spinach and lettuce, and in legumes, melons, bananas, broccoli and orange juice. Folic acid is the synthetic form of the vitamin, and it's used in fortified breads, cereals and supplements.
Eating foods rich in calcium and folic acid can have added benefits for women. If you are pregnant, or think you may become pregnant, getting enough folic acid in your diet reduces the risk of certain birth defects, and calcium helps prevent osteoporosis.
- Limit alcohol consumption. Consuming moderate to heavy amounts of alcohol — more than one drink a day for women and two for men — may increase your risk of colon cancer. This is particularly true if you have a close relative, such as a parent, child or sibling, with the disease. A drink is a 4- to 5-ounce glass of wine, a 12-ounce can of beer, or a 1.5-ounce shot of 80-proof liquor. Curbing alcohol consumption can reduce your risk, even if colon cancer runs in your family.
- Stop smoking. Smoking can increase your risk of colorectal and other cancers. Talk to your doctor about ways to quit that may work for you.
- Stay physically active and maintain a healthy body weight. Controlling your weight alone can reduce your risk of colorectal cancer. And staying physically active may cut your colon cancer risk in half. Exercise stimulates movement through your bowel and reduces the time your colon is exposed to harmful substances (carcinogens) that may cause cancer. Try to get at least 30 minutes of exercise on most days. If you've been inactive, start slowly and build up gradually to 30 minutes. Also, talk to your doctor before starting any exercise program.
- Talk with your doctor about hormone replacement therapy. If you're a woman past menopause, hormone therapy (HT) may reduce your risk of colorectal cancer. Women who use hormone therapy have a somewhat lower risk of colorectal cancer than women who don't use HT. But, women on hormone therapy who develop colorectal cancer may have a faster growing form of the disease. Also, taking HT as a combination therapy — estrogen plus progestin — can result in serious side effects and health risks. Work with your doctor to discuss the options and decide what's best for you.
- Consider taking statins for high cholesterol. A study in the May 26, 2005, issue of the "New England Journal of Medicine" found a significantly reduced risk of colorectal cancer in people who had been taking the cholesterol-lowering medications known as statins for five years or more. While the role of statins in the prevention of colorectal cancer needs to be studied further, this may be an added benefit of cholesterol-lowering therapy.
|Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.